In recent years, demands for a storage device such as a hard disk drive (HDD), with high storage capacity or recording density have steadily increased. The recording density of a magnetic recording apparatus such as a HDD may be determined according to a bits per inch (BPI) indicating the number of bits to be recorded in a unit length, and a tracks per inch (TPI) indicating the number of tracks to be included in a unit length. BPI indicates a linear recording density which is the density in a direction in which a disk rotates. TPI indicates a track density which is the density in a disk radial direction.
To increase the recording density of a magnetic recording apparatus, efforts have been made to increase the BPI and TPI. Due to the limitation in increasing the BPI, studies have been made to increase the recording density of a magnetic recording apparatus by increasing the TPI. One of the factors for dominating the TPI is the distribution of a field generated by a magnetic head of a magnetic recording apparatus. A track width may be determined by the distribution of the field, and the TPI may be determined by the track width.
In one case, a study has been made to reduce the distribution of a magnetic field by forming side shields at both sides of a main pole, to thereby increase the TPI and recording density of a magnetic recording apparatus. However, where side shields are used, the intensity of a magnetic field (a recording field) generated from a main pole may be reduced remarkably. In other words, while the distribution of a magnetic field in a track direction, for example, in a cross track direction, may be reduced by implementing the side shields, the intensity of the magnetic field may be also reduced. Accordingly, addressing the reduction in intensity of a magnetic field may be necessary where, for example, a coercivity force of a recording medium is increased gradually to improve the BPI and stability.
In another case, a discrete track recording method has been studied where tracks are separated from a recording medium by using a physical means. A discrete track medium, in which a discrete track recording method is used, has a structure in which ring-shaped data tracks are previously patterned. In this case, a region in which patterned data tracks are to be separated from one another is empty or is filled with a non-magnetic material. In a discrete track medium, interference between adjacent data tracks may be suppressed and minimized to increase the track density, thereby increasing the recording density of a magnetic recording apparatus. However, a photolithography technology which may not be currently used may be needed to manufacture such a magnetic recording medium.